1. Field of the Invention
The present invention relates to an interchangeable lens type camera system and, in particular, to an interchangeable lens type camera system having a camera body and an interchangeable lens removably attached to the camera body.
2. Description of Related Art
As widely known, a lens interchangeable camera does not have an integral construction in which a shooting lens is fixed to the camera body like a so-called compact camera. A lens interchangeable camera includes a combination of the camera body and one of multiple interchangeable lenses. The matching between the camera body and an interchangeable lens requires special consideration.
For example, in order to prevent wrong operations, power is supplied from a power supply in the camera body side to an electric circuit within an interchangeable lens at a predetermined timing after the completion of the attachment of an interchangeable lens to the camera body. This kind of power supply method is disclosed in Japanese Unexamined Patent Application Publication No. 59-048742 and Japanese Unexamined Patent Application Publication No. 62-267732.
Japanese Unexamined Patent Application Publication No. 59-048742 discloses a camera system in which multiple contact terminals at a mount portion of the camera body and multiple contact terminals at interchangeable lens are facing. In this case, the contact terminals are brought into conduction upon the completion of the lens attachment so that the power supply is turned on. In this construction, power can be easily supplied from the camera body to an interchangeable lens only by attaching the interchangeable lens to the camera body.
Japanese Unexamined Patent Application Publication No. 62-267732 discloses a camera system including a switch of which state changes upon the completion of attachment of an interchangeable lens to a camera body. Under the AND condition between the change in state of the switch and a specific operational state (such as powered-on and pressing of a release button) of the camera body, the supply of power to the interchangeable lens is started. With this construction, power can be selectively supplied from the camera body to the interchangeable lens.
However, in the interchangeable lens type camera system, whether the attached interchangeable lens is correct or not, that is, whether the attached interchangeable lens is guaranteed for correct operations or not must be checked. Sometimes, an interchangeable lens manufactured by one manufacturer may be attached to a camera body manufactured by another manufacturer. Therefore, when a lens is attached to the camera body, and when the lens is not guaranteed by the manufacturer of the camera body, appropriate camera operations may not be performed.
In view of these drawbacks, Japanese Unexamined Patent Application Publication No. 2-149073 discloses a camera system for sending test data from the camera body side to the interchangeable lens side and returning corresponding status information from the interchangeable lens side so as to determine whether the interchangeable lens attached to the camera body side is appropriate or not.